Wow! I am impressed! I have searched long and hard here in Northern California for a den site without success. I hear old timers talk about dens, but I have been skeptical because they also talk about hoop snakes etc... We have so many burrows, logs, isolated flat rocks etc., and comparatively mild Winters (no snow) that perhaps they do not den here. What gave you the faith/effort to walk that rocky area, did you just stumble onto the den or confirm your theory by searching? Congratulations, I regard that a real exciting Natural History find. Have any other forum readers found C.v.oreganus dens? How about C.v.helleri dens? Vic Herrick in Oroville, CA.